The versatility of an aircraft can be enhanced by various aircraft accessories applicable to a specific aircraft, and by making improvements and/or modifications to the aircraft to support different flight configurations. One such accessory or modification, which is the topic of the present invention, is adapting flotation devices, or more preferably skis, to the landing gear of aircraft.
Skis provide for the safe landing of an aircraft on soft surfaces such as snow (or ice) covered surfaces, soft sand, march, muskeg, tundra, etc. Thus, the ski improves the versatility of the aircraft by providing landing gear adaptable to multiple landing surfaces. This in turn improves the utility of the aircraft both by reducing the number of aircraft required to perform different missions and by adding versatility to a single aircraft during a single flight, i.e., the pilot has greater discretion when choosing an appropriate landing site.
A landing gear that becomes bogged down during a running landing or take-off can damage the landing gear, or in a worse case scenario, cause a serious accident or injury. A ski adapted to an aircraft, both fixed wing aircraft and helicopters, prevents the landing gear from penetrating the landing surface. U.S. Pat. No. 3,128,065 issued to Landes illustrates one such ski specifically designed to work in conjunction with a conventional fixed wheeled landing gear of a helicopter. The Landes patent modifies the existing landing gear by adapting a ski to the landing gear without requiring the removal of (or otherwise inhibiting the use of) the wheel portion of the wheeled landing gear. In this regard, the Landes patent provides a landing gear modification that facilitates landing the helicopter on both non-skid hard surfaces (i.e., the wheel portion of the landing gear contacts the surface prior to the generally planar lateral surface of the ski contacting the surface) and on soft surfaces (i.e., the wheel portion of the wheeled landing gear penetrates the soft surface until the weight of the helicopter is equally distributed along the generally longitudinal lateral length of the ski).
U.S. Pat. No. 2,686,023 issued to Larry illustrates an alternative aircraft ski more applicable to fixed wing aircraft. The ski of the Larry patent replaces the wheel portion of the wheeled landing gear such that the aircraft can be landed on soft surfaces and/or snow (or ice) covered hard surfaces. In this regard, while the ski of the Larry patent facilitates landing an aircraft on both non-skid hard surfaces--when the wheel portion is in place--and on soft surfaces, specifically snow covered surfaces--when the ski is in place--, because the wheel portion of the landing gear must be removed to accommodate the ski and vice versa, the aircraft cannot be landed on both non-skid hard surfaces (e.g., grass and/or pavement) and soft surfaces, during a single mission; this reduces the pilots discretionary landing options on any one flight.
Since helicopters can land and take off vertically, a ski, with or without a wheel portion, generally will not significantly interfere with the landing of the helicopter on various surfaces during a single mission, the ski merely provides sufficient surface area to support the weight of the helicopter on soft surfaces (this is not to exclude the benefits of running landings and takeoffs regarding transitional lift). However, in order to provide sufficient surface area to support the helicopter, the ski, having a significant length dimension, generally extends longitudinally rearward of the conventional landing gear into the area normally used for safe egress and ingress from the helicopter cabin. In this regard, the ski can become a safety hazard for certain egress and ingress activities such as rope repelling from the helicopter cabin during in-flight missions, or jumping from the helicopter cabin during low hover exercises. In a worst case scenario, a rope or cable may become entangled in the ski during repelling activities, thereby interfering with the safe operation of the mission, damaging the aircraft and/or injuring the persons performing the exercise. In addition, should an individual inadvertently land on the ski when jumping from the helicopter cabin, the individual could be injured or alternatively cause the aircraft to tip, with the pilot losing control of the aircraft. In any event, serious injury could occur and/or significant damage be caused to the aircraft or the landing gear (i.e., the ski) such that the aircraft cannot be landed safely.
Accordingly, there is a need for an aircraft ski, specifically a helicopter ski, that does not impede egress and ingress from the aircraft cabin, particularly with respect to rope egress and ingress from the helicopter cabin, jumping from the helicopter cabin, or use of a helicopter hoist to raise and lower cargo from the helicopter cabin.